Add r-clarabel

[cbrueffer]

Checklist

• [x] Title of this PR is meaningful: e.g. "Adding my_nifty_package", not "updated meta.yaml".
• [x] License file is packaged (see here for an example).
• [x] Source is from official source.
• [x] Package does not vendor other packages. (If a package uses the source of another package, they should be separate packages or the licenses of all packages need to be packaged).
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• [x] Package does not ship static libraries. If static libraries are needed, follow CFEP-18.
• [x] Build number is 0.
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[conda-forge-webservices[bot]]

Hi! This is the friendly automated conda-forge-linting service.

I wanted to let you know that I linted all conda-recipes in your PR (recipes/r-clarabel) and found some lint.

Here's what I've got...

For recipes/r-clarabel:

• The following maintainers have not yet confirmed that they are willing to be listed here: conda-forge/r. Please ask them to comment on this PR if they are.

For recipes/r-clarabel:

• This recipe is using a compiler, which now requires adding a build dependence on {{ stdlib("c") }} as well. Note that this rule applies to each output of the recipe using a compiler. For further details, please see https://github.com/conda-forge/conda-forge.github.io/issues/2102.